35 research outputs found
On the Performance of Multiple Antenna Cooperative Spectrum Sharing Protocol under Nakagami-m Fading
In a cooperative spectrum sharing (CSS) protocol, two wireless systems
operate over the same frequency band albeit with different priorities. The
secondary (or cognitive) system which has a lower priority, helps the higher
priority primary system to achieve its target rate by acting as a relay and
allocating a fraction of its power to forward the primary signal. The secondary
system in return is benefited by transmitting its own data on primary system's
spectrum. In this paper, we have analyzed the performance of multiple antenna
cooperative spectrum sharing protocol under Nakagami-m Fading. Closed form
expressions for outage probability have been obtained by varying the parameters
m and Omega of the Nakagami-m fading channels. Apart from above, we have shown
the impact of power allocation factor (alpha) and parameter m on the region of
secondary spectrum access, conventionally defined as critical radius for the
secondary system. A comparison between theoretical and simulated results is
also presented to corroborate the theoretical results obtained in this paperComment: Accepted in the proceedings of IEEE PIMRC 2015 Hong Kong, Chin
Outage Analysis for SWIPT-Enabled Two-Way Cognitive Cooperative Communications
In this paper, we study a cooperative cognitive radio network (CCRN) where
the secondary user-transmitter (SU-Tx) assists bi-directional communication
between a pair of primary users (PUs) following the principle of two-way
relaying. In return, it gets access to the spectrum of the PUs to enable its
own transmission to SU-receiver (SU-Rx). Further, in order to support
sustainable operation of the network, SU-Tx is assumed to harvest energy from
the RF signals received from the PUs, using the technique of simultaneous
wireless information and power transfer (SWIPT). Assuming a decode-and-forward
behaviour and power-splitting based relaying protocol at SU-Tx, closed form
expressions for outage probability of PU and SU are obtained. Simulation
results validate our analytical results and illustrate spectrum-efficiency and
energy-efficiency advantages of the proposed system over one-way relaying.Comment: 15 pages, 5 figures, Submitted to IEEE Transactions on Vehicular
Technolog
Outage Analysis for SWIPT-Enabled Two-Way Cognitive Cooperative Communications
In this paper, we study a cooperative cognitive radio network (CCRN) where
the secondary user-transmitter (SU-Tx) assists bi-directional communication
between a pair of primary users (PUs) following the principle of two-way
relaying. In return, it gets access to the spectrum of the PUs to enable its
own transmission to SU-receiver (SU-Rx). Further, in order to support
sustainable operation of the network, SU-Tx is assumed to harvest energy from
the RF signals received from the PUs, using the technique of simultaneous
wireless information and power transfer (SWIPT). Assuming a decode-and-forward
behaviour and power-splitting based relaying protocol at SU-Tx, closed form
expressions for outage probability of PU and SU are obtained. Simulation
results validate our analytical results and illustrate spectrum-efficiency and
energy-efficiency advantages of the proposed system over one-way relaying.Comment: 15 pages, 5 figures, Submitted to IEEE Transactions on Vehicular
Technolog
On Information and Energy Cooperation in Energy Harvesting Cognitive Radio
This paper considers the cooperation between primary and secondary users at
information and energy levels when both users are energy harvesting nodes. In
particular, a secondary transmitter helps relaying the primary message, and in
turn, gains the spectrum access as a reward. Also, the primary transmitter
supplies energy to the secondary transmitter if the latter is
energy-constrained, which facilitates an uninterrupted cooperation. We address
this two-level cooperation over a finite horizon with the finite battery
constraint at the secondary transmitter. While promising the rate-guaranteed
service to both primary and secondary users, we aim to maximize the primary
rate. We develop an iterative algorithm that obtains the optimal offline power
policies for primary and secondary users. To acquire insights about the
structure of the optimal solution, we examine specific scenarios. Furthermore,
we investigate the effects of the secondary rate constraint and finite battery
on the primary rate and the probability of cooperation. We show that the joint
information and energy cooperation increases the chances of cooperation and
achieves significant rate gains over only information cooperation.Comment: 6 pages, 4 figures, to be presented in IEEE PIMRC 201
Vandermonde-subspace Frequency Division Multiplexing for Two-Tiered Cognitive Radio Networks
Vandermonde-subspace frequency division multiplexing (VFDM) is an overlay
spectrum sharing technique for cognitive radio. VFDM makes use of a precoder
based on a Vandermonde structure to transmit information over a secondary
system, while keeping an orthogonal frequency division multiplexing
(OFDM)-based primary system interference-free. To do so, VFDM exploits
frequency selectivity and the use of cyclic prefixes by the primary system.
Herein, a global view of VFDM is presented, including also practical aspects
such as linear receivers and the impact of channel estimation. We show that
VFDM provides a spectral efficiency increase of up to 1 bps/Hz over cognitive
radio systems based on unused band detection. We also present some key design
parameters for its future implementation and a feasible channel estimation
protocol. Finally we show that, even when some of the theoretical assumptions
are relaxed, VFDM provides non-negligible rates while protecting the primary
system.Comment: 9 pages, accepted for publication in IEEE Transactions on
Communication
Opportunistic Adaptive Relaying in Cognitive Radio Networks
Combining cognitive radio technology with user cooperation could be
advantageous to both primary and secondary transmissions. In this paper, we
propose a first relaying scheme for cognitive radio networks (called "Adaptive
relaying scheme 1"), where one relay node can assist the primary or the
secondary transmission with the objective of improving the outage probability
of the secondary transmission with respect to a primary outage probability
threshold. Upper bound expressions of the secondary outage probability using
the proposed scheme are derived over Rayleigh fading channels. Numerical and
simulation results show that the secondary outage probability using the
proposed scheme is lower than that of other relaying schemes. Then, we extend
the proposed scheme to the case where the relay node has the ability to decode
both the primary and secondary signals and also can assist simultaneously both
transmissions. Simulations show the performance improvement that can be
obtained due to this extension in terms of secondary outage probability.Comment: 5 pages, 4 figures. Accepted for publication in Proc. IEEE
International Communications Conference (ICC), Ottawa (ON), Canada, June 201